U.S. patent application number 17/304540 was filed with the patent office on 2021-10-21 for fill on demand ampoule refill.
The applicant listed for this patent is Lam Research Corporation. Invention is credited to Chloe Baldasseroni, Ramesh Chandrasekharan, Adrien LaVoie, Tuan Nguyen, Frank Loren Pasquale, Jennifer Leigh Petraglia, Eashwar Ranganathan, Shankar Swaminathan.
Application Number | 20210324521 17/304540 |
Document ID | / |
Family ID | 1000005681920 |
Filed Date | 2021-10-21 |
United States Patent
Application |
20210324521 |
Kind Code |
A1 |
Nguyen; Tuan ; et
al. |
October 21, 2021 |
FILL ON DEMAND AMPOULE REFILL
Abstract
Methods and apparatus for use of a fill on demand ampoule are
disclosed. The fill on demand ampoule may refill an ampoule with
precursor concurrent with the performance of other deposition
processes. The fill on demand may keep the level of precursor
within the ampoule at a relatively constant level. The level may be
calculated to result in an optimum head volume. The fill on demand
may also keep the precursor at a temperature near that of an
optimum precursor temperature. The fill on demand may occur during
parts of the deposition process where the agitation of the
precursor due to the filling of the ampoule with the precursor
minimally effects the substrate deposition. Substrate throughput
may be increased through the use of fill on demand.
Inventors: |
Nguyen; Tuan; (Beaverton,
OR) ; Ranganathan; Eashwar; (Tigard, OR) ;
Swaminathan; Shankar; (Beaverton, OR) ; LaVoie;
Adrien; (Newberg, OR) ; Baldasseroni; Chloe;
(Tigard, OR) ; Chandrasekharan; Ramesh; (Portland,
OR) ; Pasquale; Frank Loren; (Tigard, OR) ;
Petraglia; Jennifer Leigh; (Portland, OR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Lam Research Corporation |
Fremont |
CA |
US |
|
|
Family ID: |
1000005681920 |
Appl. No.: |
17/304540 |
Filed: |
June 22, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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14720595 |
May 22, 2015 |
11072860 |
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17304540 |
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14516452 |
Oct 16, 2014 |
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14720595 |
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62040974 |
Aug 22, 2014 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C23C 16/52 20130101;
C23C 16/448 20130101 |
International
Class: |
C23C 16/52 20060101
C23C016/52; C23C 16/448 20060101 C23C016/448 |
Claims
1. A substrate processing apparatus, comprising: an ampoule
configured to be fluidically connected to a precursor delivery
system and a precursor source and configured to contain liquid
precursor; and one or more controllers configured to: (a) determine
that an ampoule fill start condition for filling the ampoule with a
liquid precursor is met; (b) fill the ampoule with precursor,
wherein filling the ampoule with the precursor is performed
concurrent with at least one other substrate processing operation;
(c) determine that a sensor level in the ampoule indicates that the
ampoule is not full, wherein a primary fill stop condition is met
when the sensor level in the ampoule indicates that the ampoule is
full; (d) maintain a cumulative time of filling the ampoule,
wherein the cumulative time of filling the ampoule is all of the
time that the precursor is flowing to the ampoule since the
cumulative time of filling the ampoule was last reset, wherein the
cumulative time of filling the ampoule is reset when the sensor
level in the ampoule indicates that the ampoule is full (e)
determine that a secondary fill stop condition is met, wherein the
secondary fill stop condition comprises determining that the
cumulative time of filling exceeds a threshold; and (e) in response
to determining that the secondary fill stop condition is met and in
response to determining that the sensor level in the ampoule
indicates that the ampoule is not full, cease the filling of the
ampoule with the precursor.
2. The substrate processing apparatus of claim 1, wherein the one
or more controllers are further configured to temporarily stop the
cumulative time of filling one or more times when ampoule refill
temporarily ceases and deposition commences.
3. The substrate processing apparatus of claim 1, wherein the
threshold is between about 50 seconds and 90 seconds.
4. The substrate processing apparatus of claim 1, wherein the one
or more controllers are further configured to initiate a soft
shutdown when ceasing the filling in operation (e).
5. The substrate processing apparatus of claim 1, wherein the
ampoule fill start condition comprises determining that the
substrate processing apparatus is in or is about to enter a phase
after one or more substrates have been loaded into a substrate
processing chamber of the substrate processing apparatus, before
any of the one or more substrates have been unloaded from the
substrate processing chamber, and while deposition is not occurring
in the substrate processing apparatus.
6. The substrate processing apparatus of claim 1, wherein the
ampoule fill start condition comprises determining that a sequence
of deposition operations has been completed on substrates contained
in the substrate processing apparatus.
7. The substrate processing apparatus of claim 1, wherein the
ampoule fill start condition includes determining that the
precursor volume is below a threshold volume.
8. The substrate processing apparatus of claim 1, wherein the
ampoule fill start condition includes determining that setup for
deposition operations is currently being performed.
9. The substrate processing apparatus of claim 1, wherein the at
least one other substrate processing operation that is performed
concurrent with filling the ampoule includes a wafer indexing
operation.
10. The substrate processing apparatus of claim 1, wherein the at
least one other substrate processing operation that is performed
concurrent with filling the ampoule includes a temperature soak of
the precursor and/or a substrate.
11. The substrate processing apparatus of claim 1, wherein the at
least one other substrate processing operation that is performed
concurrent with filling the ampoule includes a pump to base
operation.
12. The substrate processing apparatus of claim 1, further
comprising: a deposition chamber; and a substrate processing
station contained within the deposition chamber, wherein the
substrate processing station includes a substrate holder configured
to receive a substrate and the precursor delivery system is
configured to deliver precursor during processing of the substrate
received by the substrate processing station.
13. A method for controlling the filling an ampoule of a substrate
processing apparatus comprising: (a) starting a counter of a number
of deposition cycles during which a precursor is delivered to a
reaction chamber of the substrate processing apparatus, wherein the
precursor is stored in liquid form in the ampoule; (b) determining
that an ampoule fill start condition is met; (c) reading a sensor
level in the ampoule indicating that the ampoule is sufficiently
full that the precursor should not be provided to the ampoule; (d)
determining that a number of deposition cycles counted by the
counter exceeds a threshold; and (e) in response to determining
that the number of deposition cycles counted by the counter exceeds
the threshold, ceasing the deposition cycles.
14. The method of claim 13, wherein the threshold comprises between
about 3000 and 6000 deposition cycles.
15. The method of claim 13, wherein starting the counter in (a)
occurs when the precursor is delivered to the ampoule, and wherein
the counter continues to count until the precursor is again
delivered to the ampoule.
16. The method of claim 13, further comprising initiating a soft
shutdown when ceasing the deposition cycles in operation (e).
17. The method of claim 13, wherein the sensor generating the
sensor level in the ampoule is malfunctioning.
18. The method of claim 13, wherein the ampoule fill start
condition comprises determining that the substrate processing
apparatus is in or is about to enter a phase during which agitation
of the precursor caused by filling the ampoule with the precursor
would have a minimal effect on the consistency of substrates
processed by the substrate processing apparatus.
19. The method of claim 13, wherein the ampoule fill start
condition comprises determining that a sequence of deposition
operations has been completed on substrates contained in the
substrate processing apparatus.
20. The method of claim 15, wherein the sequence of deposition
operations are deposition operations associated with Atomic Layer
Deposition.
21. The method of claim 13, wherein the ampoule fill start
condition includes determining that setup for deposition operations
is currently being performed.
22. The method of claim 13, wherein the ampoule fill condition
comprises one other substrate processing operation that is
performed concurrent with filling the ampoule selected from the
group consisting of a wafer indexing operation, a temperature soak
of the precursor and/or a substrate, a pump to base operation.
23. A precursor refill system comprising: an ampoule configured to
be fluidically connected to a precursor delivery system and a
precursor source and configured to contain liquid precursor; and
one or more controllers configured to: (a) start a counter of a
number of deposition cycles during which a precursor is delivered
to a reaction chamber of a substrate processing apparatus, wherein
the precursor is stored in liquid form in the ampoule; (b)
determine that an ampoule fill start condition is met; (c) read a
sensor level in the ampoule indicating that the ampoule is
sufficiently full that the precursor should not be provided to the
ampoule; (d) determine that a number of deposition cycles counted
by the counter exceeds a threshold; and (e) in response to
determining that the number of deposition cycles counted by the
counter exceeds the threshold, cease the deposition cycles.
24. The precursor refill system of claim 23, wherein the threshold
comprises between about 3000 and 6000 deposition cycles.
25. The precursor refill system of claim 23, wherein the one or
more controllers are further configured to start the counter in (a)
when the precursor is delivered to the ampoule, and continue to
count until the precursor is again delivered to the ampoule.
26. The precursor refill system of claim 23, wherein the one or
more controllers are further configured to initiate a soft shutdown
when ceasing the deposition cycles in operation (e).
27. The precursor refill system of claim 26, wherein the ampoule
fill start condition comprises determining that the substrate
processing apparatus is in or is about to enter a phase during
which agitation of the precursor caused by filling the ampoule with
the precursor would have a minimal effect on the consistency of
substrates processed by the substrate processing apparatus.
28. The precursor refill system of claim 23, wherein the ampoule
fill start condition comprises determining that a sequence of
deposition operations has been completed on substrates contained in
the substrate processing apparatus.
29. The precursor refill system of claim 23, wherein the ampoule
fill condition comprises one other substrate processing operation
that is performed concurrent with filling the ampoule selected from
the group consisting of a wafer indexing operation, a temperature
soak of the precursor and/or a substrate, a pump to base
operation.
30. The substrate processing apparatus of claim 23, further
comprising: a deposition chamber; and a substrate processing
station contained within the deposition chamber, wherein the
substrate processing station includes a substrate holder configured
to receive a substrate and the precursor delivery system is
configured to deliver precursor during processing of the substrate
received by the substrate processing station.
Description
INCORPORATION BY REFERENCE
[0001] An Application Data Sheet is filed concurrently with this
specification as part of the present application. Each application
that the present application claims benefit of or priority to as
identified in the concurrently filed Application Data Sheet is
incorporated by reference herein in their entireties and for all
purposes.
BACKGROUND
[0002] Certain substrate processing operations may utilize a
precursor. The precursor may be contained in an ampoule and
periodically delivered to a reactor. Consistent head volume and
consistent precursor temperature may be desired to ensure the
uniformity of substrates processed. Additionally, agitation of the
precursor from refilling may be undesirable when substrates are
processed. Refill takes time and may affect reduce throughput.
SUMMARY
[0003] In certain implementations, a method for refilling an
ampoule of a substrate processing apparatus may be detailed. The
method may include: (a) determining that an ampoule refill start
condition is met, wherein the ampoule refill start condition
comprises determining that the substrate processing apparatus is or
is about to enter a phase during which agitation of the precursor
caused by refilling the ampoule with the precursor would have a
minimal effect on the consistency of substrates processed by the
substrate processing apparatus, (b) refilling the ampoule with
precursor, wherein refilling the ampoule with the precursor is
performed concurrent with at least one other substrate processing
operation, (c) determining that an ampoule refill stop condition is
met, and (d) ceasing the refilling of the ampoule with the
precursor.
[0004] One aspect of the disclosure pertains to methods for filling
an ampoule of a substrate processing apparatus. Such methods may be
characterized by the following operations: (a) determining that an
ampoule fill start condition for filling the ampoule with a liquid
precursor is met; (b) filling the ampoule with precursor, wherein
filling the ampoule with the precursor is performed concurrent with
at least one other substrate processing operation; (c) reading a
sensor level in the ampoule indicating that the filling is not yet
complete; (d) determining that a secondary fill stop condition is
met; and (e) in response to determining that the secondary fill
stop condition is met, ceasing the filling of the ampoule with the
precursor.
[0005] In certain embodiments, the methods further include
maintaining a cumulative time of filling starting at the end of the
last time when the ampoule received the precursor. In some
implementations, the secondary fill stop condition involves
determining that the cumulative time of filling exceeds a
threshold. In some implementations, the cumulative time of filling
is temporarily stopped one or more times when ampoule refill
temporarily ceases and deposition commences, but the cumulative
time of filling restarts when filling starts again. In some
implementations, the threshold is between about 50 seconds and 90
seconds.
[0006] In certain embodiments, the methods include initiating a
soft shutdown when ceasing the filling in operation (e). In some
cases, the method is executed when the sensor generating the sensor
level in the ampoule is malfunctioning. In some cases, the method
is executed when a system providing the liquid precursor to the
ampoule is malfunctioning.
[0007] In certain embodiments, the ampoule fill start condition
involves determining that the substrate processing apparatus is in
or is about to enter a phase during which agitation of the liquid
precursor caused by filling the ampoule with the precursor would
have a minimal effect on the consistency of substrates processed by
the substrate processing apparatus. In some embodiments, the
ampoule fill start condition involves determining that a sequence
of deposition operations has been completed on substrates contained
in the substrate processing apparatus. In some cases, the sequence
of deposition operations are deposition operations associated with
Atomic Layer Deposition. In certain embodiments, the ampoule fill
start condition includes determining that the precursor volume is
below a threshold volume. In certain embodiments, the ampoule fill
start condition includes determining that setup for deposition
operations is currently being performed.
[0008] In some implementations, the at least one other substrate
processing operation that is performed concurrent with filling the
ampoule includes a wafer indexing operation. In some cases, the at
least one other substrate processing operation that is performed
concurrent with filling the ampoule includes a temperature soak of
the precursor and/or the substrate. In some cases, the at least one
other substrate processing operation that is performed concurrent
with filling the ampoule includes a pump to base operation.
[0009] Some aspects of the disclosure pertain to methods for
controlling the filling an ampoule of a substrate processing
apparatus. Such methods may be characterized by the following
operations: (a) starting a counter of the number of deposition
cycles during which a precursor is delivered to a reaction chamber
of the substrate processing apparatus, wherein the precursor is
stored in liquid form in the ampoule; (b) determining that an
ampoule fill start condition is met; (c) reading a sensor level in
the ampoule indicating that the ampoule is sufficiently full that
the liquid precursor should not be provided to the ampoule; (d)
determining that a number of deposition cycles counted by the
counter exceeds a threshold; and (e) in response to determining
that the number of deposition cycles counted by the counter exceeds
a threshold, ceasing the deposition cycles. In some
implementations, the threshold is between about 3000 and 6000
deposition cycles.
[0010] In certain embodiments, starting the counter in (a) occurs
when the liquid precursor is delivered to the ampoule, and the
counter continues to count until liquid precursor is again
delivered to the ampoule. In some implementations, he method
includes initiating a soft shutdown when ceasing the deposition
cycles in operation (e).
[0011] In some cases, the method is executed when the sensor
generating the sensor level in the ampoule is malfunctioning. In
certain embodiments, the ampoule fill start condition includes
determining that the substrate processing apparatus is in or is
about to enter a phase during which agitation of the liquid
precursor caused by filling the ampoule with the precursor would
have a minimal effect on the consistency of substrates processed by
the substrate processing apparatus. In certain embodiments, the
ampoule fill start condition includes determining that a sequence
of deposition operations has been completed on substrates contained
in the substrate processing apparatus. In some examples, the
sequence of deposition operations are deposition operations
associated with Atomic Layer Deposition.
[0012] In some implementations, the ampoule fill start condition
includes determining that setup for deposition operations is
currently being performed. In some implementations, the ampoule
fill condition includes one other substrate processing operation
that is performed concurrent with filling the ampoule selected from
the group consisting of a wafer indexing operation, a temperature
soak of the precursor and/or the substrate, a pump to base
operation.
[0013] Some aspects of the disclosure pertain to precursor refill
systems, which may be characterized by the following features: (1)
an ampoule configured to be fluidically connected to a precursor
delivery system and a precursor source and configured to contain
liquid precursor; and (2) one or more controllers configured to:
(a) start a counter of the number of deposition cycles during which
a precursor is delivered to a reaction chamber of the substrate
processing apparatus, wherein the precursor is stored in liquid
form in the ampoule; (b) determine that an ampoule fill start
condition is met; (c) read a sensor level in the ampoule indicating
that the ampoule is sufficiently full that the liquid precursor
should not be provided to the ampoule; (d) determine that a number
of deposition cycles counted by the counter exceeds a threshold;
and (e) in response to determining that the number of deposition
cycles counted by the counter exceeds a threshold, cease the
deposition cycles. In some implementations, the threshold comprises
between about 3000 and 6000 deposition cycles.
[0014] In some designs, the one or more controllers are further
configured to start the counter in (a) when the liquid precursor is
delivered to the ampoule, and continue to count until liquid
precursor is again delivered to the ampoule. In some
implementations, the one or more controllers are further configured
to initiate a soft shutdown when ceasing the deposition cycles in
operation (e).
[0015] In certain embodiments, the ampoule fill start condition
includes determining that the substrate processing apparatus is in
or is about to enter a phase during which agitation of the liquid
precursor caused by filling the ampoule with the precursor would
have a minimal effect on the consistency of substrates processed by
the substrate processing apparatus. In certain embodiments, the
ampoule fill start condition includes determining that a sequence
of deposition operations has been completed on substrates contained
in the substrate processing apparatus. In certain embodiments, the
ampoule fill condition includes one other substrate processing
operation that is performed concurrent with filling the ampoule
selected from the group consisting of a wafer indexing operation, a
temperature soak of the precursor and/or the substrate, a pump to
base operation.
[0016] In some implementations, the substrate processing apparatus
includes: a deposition chamber; and a substrate processing station
contained within the deposition chamber, wherein the substrate
processing station includes a substrate holder configured to
receive a substrate and the precursor delivery system is configured
to deliver precursor during processing of the substrate received by
the substrate processing station.
[0017] Another aspect of the disclosure pertains to a precursor
refill system including: (1) an ampoule configured to be
fluidically connected to a precursor delivery system and a
precursor source and configured to contain liquid precursor; and
(2) one or more controllers configured to: (a) determine that an
ampoule fill start condition for filling the ampoule with a liquid
precursor is met; (b) fill the ampoule with precursor, wherein
filling the ampoule with the precursor is performed concurrent with
at least one other substrate processing operation; (c) read a
sensor level in the ampoule indicating that the filling is not yet
complete; (d) determine that a secondary fill stop condition is
met; and (e) in response to determining that the secondary fill
stop condition is met, cease the filling of the ampoule with the
precursor.
[0018] In certain embodiments, the one or more controllers are
further configured to maintain a cumulative time of filling
starting at the end of the last time when the ampoule received the
precursor. In some cases, the secondary fill stop condition
includes determining that the cumulative time of filling exceeds a
threshold. In some implementations, the one or more controllers are
further configured to temporarily stop the cumulative time of
filling one or more times when ampoule refill temporarily ceases
and deposition commences.
[0019] In some implementations, the threshold is between about 50
seconds and 90 seconds. In some implementations, the one or more
controllers are further configured to initiate a soft shutdown when
ceasing the filling in operation (e).
[0020] In certain embodiments, the ampoule fill start condition
includes determining that the substrate processing apparatus is in
or is about to enter a phase during which agitation of the liquid
precursor caused by filling the ampoule with the precursor would
have a minimal effect on the consistency of substrates processed by
the substrate processing apparatus. In certain embodiments, the
ampoule fill start condition includes determining that the
precursor volume is below a threshold volume. In some
implementations, the at least one other substrate processing
operation that is performed concurrent with filling the ampoule
includes a temperature soak of the precursor and/or the
substrate.
[0021] In some embodiments, substrate processing apparatus
includes: a deposition chamber; and a substrate processing station
contained within the deposition chamber, wherein the substrate
processing station includes a substrate holder configured to
receive a substrate and the precursor delivery system is configured
to deliver precursor during processing of the substrate received by
the substrate processing station.
[0022] These and other features of the invention will be described
in more detail below with reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1A shows a schematic representation of an example
substrate processing apparatus with a fill on demand ampoule.
[0024] FIG. 1B shows a schematic representation of another example
substrate processing apparatus with a fill on demand ampoule.
[0025] FIG. 2 is a process flow diagram detailing an example
deposition process operation utilizing a fill on demand
ampoule.
[0026] FIG. 3 is a process flow diagram detailing an algorithm to
control an example fill on demand ampoule.
[0027] FIG. 4A shows a step in substrate processing for the example
substrate processing apparatus of FIG. 1A.
[0028] FIG. 4B shows another step in substrate processing for the
example substrate processing apparatus of FIG. 1A.
[0029] FIG. 4C shows an additional step in substrate processing for
the example substrate processing apparatus of FIG. 1A.
[0030] FIG. 4D shows a further step in substrate processing for the
example substrate processing apparatus of FIG. 1A.
[0031] FIG. 5 is a comparison of substrate processing results for
substrate processing with fill on demand versus substrate
processing without fill on demand.
[0032] FIG. 6 illustrates an ampoule with a sensor and multiple
sensor levels suitable for providing protection against overfill
and under fill.
[0033] FIG. 7 presents a flow chart for an implementation of
ampoule overfill protection.
[0034] FIG. 8 presents a flow chart for an implementation of
ampoule low liquid level protection.
DETAILED DESCRIPTION
[0035] Details of one or more implementations of the subject matter
described in this specification are set forth in the accompanying
drawings and the description below. Other features, aspects, and
advantages will become apparent from the description, the drawings,
and the claims. Note that the relative dimensions of the following
figures may not be drawn to scale unless specifically indicated as
being scaled drawings.
[0036] It is to be understood that, as used herein, the term
"semiconductor wafer" may refer both to wafers that are made of a
semiconductor material, e.g., silicon, and wafers that are made of
materials that are not generally identified as semiconductors,
e.g., dielectrics and/or conductors, but that typically have
semiconductor materials provided on them. Silicon on insulator
(SOI) wafers are one such example. The apparatuses and methods
described in this disclosure may be used in the processing of
semiconductor wafers of multiple sizes, including 200 mm, 300 mm,
and 450 mm diameter semiconductor wafers.
[0037] Uniformity is an important factor in the processing of high
quality semiconductor wafers. For example, the thickness and
quality of a deposited layer should be uniform from wafer-to-wafer
and within features of a wafer. In certain implementations of
semiconductor processing, a liquid precursor may need to be
evaporated before being deposited on a semiconductor wafer. The
liquid precursor may be contained in an ampoule and a carrier gas,
such as argon or other inert gasses, and may flow through the
ampoule to carry evaporated precursor to a semiconductor processing
chamber. Carrier gas may be either "pushed" (where gas is forced
through the lines) or "pulled" (where gas is pulled through the
lines, possibly via a vacuum) through the ampoule to carry the
evaporated precursor. In certain deposition processes, such as
Atomic Layer Deposition (ALD), wafer uniformity may benefit from a
relatively constant head volume of gas within the ampoule as well
as a constant precursor temperature. In certain such
implementations, the targeted head volume may be a volume of about
20-30% of the ampoule volume. Thus, about 70-80% of the ampoule may
be filled with precursor when the head volume is about 20-30% of
the ampoule volume. Further, wafer uniformity may also benefit from
a lack of precursor agitation resulting in uneven evaporation of
the precursor. Finally, high wafer throughput is important in the
manufacture of semiconductor wafers. Currently, ampoules are
typically refilled through manual fill, automatic fill,
simultaneous fill, or refilled during maintenance. However, none of
the current techniques combine a fairly constant head volume and
precursor temperature when used during deposition, lack of
precursor agitation during deposition, and high wafer
throughput.
[0038] FIG. 1A shows a schematic representation of an example
substrate processing apparatus with a fill on demand ampoule. FIG.
1A shows a substrate processing apparatus 100 with an ampoule 102
and a processing chamber 132.
[0039] The ampoule 102 contains precursor 104 in the representation
shown in FIG. 1A. In certain implementations, the ampoule may have
a volume of between about 600 mL to 3 L. In the implementation
shown, the ampoule may be an ampoule of about 1.2 L. The precursor
flows into the ampoule 102 through a flow path 112. A valve 114
controls the flow through precursor through the flow path 112. When
the valve 114 is open, precursor may flow through the flow path 112
into the ampoule 102, filling the ampoule 102. When the valve 114
is closed, precursor may not flow into the ampoule 102. In the
implementation shown, the flow path 112 is a flow path connected to
the bottom of the ampoule 102. In other implementations, the flow
path containing the precursor may be other configurations such as a
dipstick and may fill the ampoule in areas other than from the
bottom of the ampoule.
[0040] The processing chamber 132 includes a manifold 120 and a
showerhead 122. Certain implementations may include more than one
showerhead, such as two showerheads or four showerheads. In such
implementations, the manifold may distribute fluids to the
showerheads. Certain other implementations may replace the manifold
with another device for the distribution of precursors, such as an
injector. In other implementations, the processing chamber may not
contain a manifold.
[0041] The showerhead 122 may be fluidically connected to the
manifold 120 through a flow path 138 and a valve 130 may be
installed on the flow path to control the flow of fluids from the
manifold 120 to the showerhead 122. The showerhead 122 may
distribute fluids that flow through the flow path 138 to process
stations located in the processing chamber 132. The process
stations may contain substrates. The process stations are not shown
in FIG. 1A.
[0042] The manifold 120 may also be connected to a vacuum through
other flow paths. The valve 128 may control the vacuum. In certain
implementations, at most one of the valves 130 and 128 may be open
at any given time. The vacuum may be used to allow for the
continuous flow of carrier gas and/or precursor gas when the
showerhead 122 is not ready to receive the flow of fluids.
[0043] Flow paths 118 and 136 connect the ampoule 102 to the
manifold 120. A valve 126 is located on flow path 118. The valve
126 controls the flow of all fluids to the manifold 120; when the
valve 126 is closed, no fluids may flow to the manifold 120.
Conversely, when the valve 126 is opened, fluids may flow to the
manifold. Additionally, a valve 124 is also located on flow path
118. The valve 124 controls the flow of carrier gas to the valve
126.
[0044] A valve 116 is located on flow path 136. The valve 116
controls the flow of precursor gas from the ampoule 102 to the
valve 126.
[0045] Flow path 106 connects the substrate processing apparatus
100 with a source of carrier gas. The flow of the carrier gas
through the flow path 106 into the rest of the flow paths of the
substrate processing apparatus 100 is controlled by a valve 108. If
the valve 108 is closed, there may be no fluid flow through the
substrate processing apparatus 100.
[0046] Flow path 134 connects the flow path 106 with the ampoule
102. A valve 110 located on flow path 134 controls the flow of
carrier gas from the flow path 106 into the ampoule 102. After the
carrier gas flows into the ampoule 102, it may mix with evaporated
precursor to form the precursor gas.
[0047] The flow of fluids through the substrate processing
apparatus 100 may be controlled through the opening and closing of
the various valves. Certain configurations of opened and closed
valves will be discussed in greater detail in FIGS. 4A through
4D.
[0048] FIG. 1B shows a schematic representation of another example
substrate processing apparatus with a fill on demand ampoule. The
substrate processing apparatus 100B in FIG. 1B is similar to the
substrate processing apparatus 100 in FIG. 1A. Substrate processing
apparatus 100B includes an additional valve 140 connected by flow
path 142. In the implementation of FIG. 100B shown in FIG. 1B, the
flow path 142 and the valve 140 may offer an additional path for
carrier gas to flow to the valve 126. In certain implementations,
the flow path through the valve 124 may be used to flow carrier gas
during operation of the substrate processing apparatus, while the
flow path through the valve 140 may be used to flow carrier gas
during maintenance of the substrate processing apparatus.
[0049] FIG. 2 is a process flow diagram detailing an example
deposition process operation utilizing a fill on demand ampoule.
FIG. 2 details ampoule fill operations and the timetable of the
ampoule fill operations as compared to the rest of the process
operations. In FIG. 2, ampoule fill operations are shown on the
right side of the figure while other deposition process operations
are shown on the left side. The process operation detailed in FIG.
2 may be an ALD processing operation, or may be other types of
substrate processing operations that use a liquid reactant such as
chemical vapor deposition, etching operations including atomic
layer etching, and the like.
[0050] In operation 202, setup of the process operation is carried
out. Operation 202 includes many different tasks that are involved
in the setting up of processing operations such as general checking
of the apparatus, the lifting of pins, the loading of substrates,
and the programming of operations.
[0051] After operation 202, operation 204 starts the filling of the
ampoule. Operation 204 begins the initial filling of the ampoule.
At the beginning of operation 204, the ampoule may be completely
empty.
[0052] While the ampoule is being filled, temperature soak occurs
in operation 206. The temperature soak may heat the precursor to
bring it to a desired temperature, such as between about 20 to 100
degrees Celsius for certain precursors used in ALD, and/or it may
heat the substrate prior to deposition. The temperature that the
precursor is heated to may be dependent on the chemical composition
of the precursor. Certain implementations may heat the precursor
and/or the substrate from room temperature up to a higher
temperature (e.g., a temperature between about 25-45 degrees
Celsius). Other implementations may heat the precursor and/or the
substrate from room temperature up to a temperature of between
about 25-60 degrees Celsius while yet other implementations may
heat the precursor and/or the substrate from room temperature up to
an even higher temperature (e.g., up to about 80 degrees Celsius).
The heat soaking of the precursor as it is being filled may result
in a precursor that is at the optimum temperature for the precursor
to evaporate to the desired amount. Additionally, heat soaking the
precursor during the filling of the ampoule may allow for greater
substrate throughput since two setup operations are being performed
concurrently. Finally, since no carrier gas is being flowed through
the ampoule to carry evaporated precursor gas, filling the ampoule
during heat soak also may minimize the effect resulting from
agitation of the precursor during filling.
[0053] After the temperature soak of operation 206 is complete, but
before the lines are charged in operation 210, the ampoule ceases
being filled in operation 208. The ampoule may cease being filled
due to a variety of different conditions. Such conditions are
described in greater detail in FIG. 3. In certain implementations,
the ampoule may initially be at a full level. In such
implementations, the initial filling of the ampoule may be
skipped.
[0054] In operation 210, line charge is performed. Line charge is
the flow of gas through the flow paths of the substrate processing
apparatus prior to delivering the precursor gas into the processing
chamber. In other words, the lines leading to the chamber are
charged to eliminate delay when the valves to the chamber are
opened. For example, certain implementations may flow the carrier
gas through various flow paths to carry precursor gas from the
ampoule. The pre-flowing of such precursor gas may aid in having
more consistent initial cycles of deposition by pre-charging the
flow paths with precursor gas used in deposition such that when the
valve to leading to the processing chamber is switched open,
precursor gas is quicker to arrive in the processing chamber.
[0055] After the line charge in operation 210, deposition is
performed in operation 212. Deposition performed in operation 212
may be a single cycle of deposition, or may be multiple cycles of
deposition such as that performed during ALD.
[0056] After deposition is performed in operation 212, secondary
ampoule filling is started in operation 216. The secondary ampoule
filling in operation 216 may fill the ampoule back to a full level
or may be designed to fill the ampoule until another stop fill
condition is met. When a stop fill condition is met in operation
220, the second ampoule filing operation ceases. The secondary
ampoule filling allows the ampoule to maintain a relatively
consistent head volume, leading to greater wafer uniformity. During
secondary ampoule filling, the ampoule may be heated to allow for
more consistent precursor temperatures. In certain implementations
such as the implementation described in FIG. 2, the secondary
ampoule filling is timed to occur during a period when the
agitation of the precursor resulting from the filling has a minimal
effect on the substrate processing. In some implementations, such
periods may be periods when no deposition is performed. In other
implementations, deposition may be performed during such periods if
the vapor pressure of the precursor is below a certain threshold.
Precursors with low vapor pressures may be less sensitive to
agitation from refilling and so may be more suitable to be refilled
while deposition is performed. For example, precursors with a vapor
pressure less than about 1 Torr are precursors that may be refilled
during deposition. In certain implementations, the amount of
precursor refilled during any single operation of secondary ampoule
filling may be less than about 40% of the total ampoule volume,
such as less than about 20%, less than about 10%, less than about
5%, or less than about 2% of the total ampoule volume.
[0057] While the secondary ampoule filling is performed, other
process operations are still being performed, such as pump to base
and wafer indexing. In operation 214, pump to base is performed.
Pump to base is a process of evacuating a chamber to a base
pressure provided by a vacuum pump. The process removes residual
materials from the substrate processing chamber through, for
example, vacuum ports in the processing chamber.
[0058] In operation 218, wafer indexing is performed. Wafer
indexing is the transfer and orientation of substrates to an
additional process station within the substrate processing chamber.
Wafer indexing may be performed when the substrate processing
chamber has multiple processing stations. In certain
implementations, such as implementations involving a processing
chamber with only one processing station, wafer indexing may not be
performed.
[0059] After wafer indexing in operation 218, the process may
proceed back to operation 212 and perform deposition again until
all require deposition has been performed. Ampoule filling may be
performed between each round of deposition.
[0060] FIG. 3 is a process flow diagram detailing an algorithm to
control an example fill on demand ampoule. In operation 302, a
command is given to perform precursor fill. Operation 302 may
correspond to operations 204 or 216 in FIG. 2. The command to
perform the precursor fill may be given through logic contained in
a controller. The controller may be a controller used to control
other deposition operations of the substrate processing apparatus,
or it may be a separate controller dedicated to controlling
operations associated with the ampoule.
[0061] Once the command is given to perform the precursor fill,
precursor begins to fill the ampoule. While the precursor fill is
performed, the controller may also concurrently perform operations
304, 306, and 308.
[0062] In operation 304, the controller checks to see if the
ampoule full sensor is on. The ampoule may contain a level sensor
such as a discrete level sensor. The level sensor may be set to
detect a certain precursor level within the ampoule such as the
full level. Such a precursor full level may be calculated to result
in an ampoule that contains an optimum head volume. In certain
implementations, the full level may be a threshold volume
calculated to arrive at the optimum head volume. Such threshold
volumes may be, for example, a volume of precursor of around about
70-80% of the total volume of the ampoule such as about 75% of the
total volume of the ampoule. In other implementations, the
threshold volume may be a range of volumes. In such
implementations, a precursor volume falling within the range may
satisfy the full condition. In certain such implementations,
subsequent secondary ampoule fillings may be adjusted based on the
detected precursor volume. For example, the stop conditions of the
subsequent secondary ampoule fillings may be adjusted.
[0063] In certain other implementations, the level sensor may
report a low level. The low level may be reported when the volume
of the precursor within the ampoule is below a threshold percentage
of the ampoule volume. In such implementations, the threshold
volume may be a volume of less than about 50% of the ampoule
volume. In such implementations, the substrate processing apparatus
may stop the processing of substrates when the level sensor reports
a low level. In certain implementations, the substrate processing
apparatus may finish all deposition cycles in a sequence of
substrate deposition operations before stopping the substrate
processing to refill the ampoule.
[0064] In operation 306, the controller checks to see if the
ampoule fill timer has expired. The ampoule fill timer may be a
timer set in the controller such that the ampoule fill process is
performed for only a duration close to the duration that would be
required to fill the ampoule to the full level. In certain
implementations, the fill timer may be a duration slightly longer
than the time required to fill the ampoule to the full level in
order to introduce some safety factor. In other implementations,
the ampoule fill timer may be much longer than the duration
required to fill the ampoule to full. In such implementations, the
fill timer duration may be selected to allow the best opportunity
to fill the ampoule to a full level and the ampoule full sensor may
be relied upon as the primary mechanism to prevent overfilling of
the ampoule.
[0065] In certain implementations, the fill timer for the initial
fill and the secondary fill may be different. In such
implementations, the initial fill timer may be, for example, 45
seconds or less, while the secondary fill timer may be, for
example, between 5 to 10 seconds. In other implementations, the
fill timer may be adjusted based on a correction factor. The
correction factor may be a factor to account for the differences in
pressures of the refill lines of various different substrate
processing apparatus. Thus, a substrate processing apparatus that
has a high refill line pressure may have a low correction factor
resulting in a shorter fill timer, while a substrate processing
apparatus that has a low refill line pressure may have a high
correction factor resulting in a longer fill timer. The refill line
pressure may vary based on inherent properties of the substrate
processing apparatus, or it may vary based on operators' experience
with a particular piece of equipment. For example, the refill line
pressure may be decreased if a further decrease in precursor
agitation is desired. In addition, the correction factor may
account for any variation upstream of a pressure indicator within
the precursor refill line. Factors that may affect the line
pressure include the diameter and length of the refill line.
[0066] In certain implementations, the secondary fill timer may
stay constant regardless of the conditions detected during the
initial fill. In other implementations, the secondary fill timer
may be adjusted depending on conditions detected during the initial
fill. For example, if, during initial fill, the ampoule full sensor
was never detected to be on, the duration of the secondary fill
timer may be lengthened to allow for a greater likelihood of the
ampoule reaching a full level during the secondary fill
operation.
[0067] In operation 308, the controller checks to see if an
explicit stop command has been called. In certain implementations,
an explicit stop command to cease filling the ampoule may be
programmed into the controller before the performance of certain
deposition steps, such as deposition steps where concurrent filling
of the ampoule during performance of the steps may result in
unacceptable agitation of the precursor. The explicit stop command
may be a further safeguard against the failure of the ampoule full
sensor and/or the ampoule fill timer. Additionally, the fill timer
and/or the full volume may be user defined parameters in certain
implementations. The explicit stop command may prevent errors in
the user definition of the parameters from affecting the quality of
substrate processing.
[0068] If the controller detects a "yes" result from any of
operations 304, 306, or 308, the controller then proceeds to
operation 310 and the precursor fill is stopped. If no "yes" result
is detected from any of operations 304, 306, or 308, the controller
may return to operation 302 and continue performing the precursor
fill.
[0069] FIG. 4A shows a step in substrate processing for the example
substrate processing apparatus of FIG. 1A. The step shown in FIG.
4A corresponds to operation 204 of FIG. 2. The substrate processing
apparatus 100 shown in FIG. 4A, as well as FIGS. 4B-C, may be a
substrate processing apparatus with a similar configuration to that
of the substrate processing apparatus shown in FIG. 1A. In FIGS.
4A-D, solid lines represent flow paths with no flow, dotted lines
represent flow paths with liquid precursor flow, broken lines
represent flow paths with carrier gas flow, and broken and dotted
lines represent flow paths with precursor gas flow.
[0070] In FIG. 4A, initial filling of the ampoule 102 is being
performed. In the implementation shown in FIG. 4A, all valves
except for valve 114 are closed. Valve 114 is open to allow the
flow of the precursor into the ampoule 102. In other
implementations, valves 108, 124, 126, and 128 may be open. The
ampoule 102 may be heated in FIG. 4A in order to bring the
precursor to a desired temperature to facilitate evaporation of the
precursor.
[0071] FIG. 4B shows another step in substrate processing for the
example substrate processing apparatus of FIG. 1A. The step shown
in FIG. 4B corresponds to operation 210 of FIG. 2. In FIG. 4B,
valve 114 is now closed as at least one of the conditions required
to stop the filling of the precursor has been triggered.
[0072] In FIG. 4B, valves 108, 110, 116, and 126 are open to allow
the substrate processing apparatus to pre-charge flow paths 118 and
136 with precursor gas flow. Since the showerhead 122 is not ready
to receive the precursor gas flow in FIG. 2, the precursor gas that
flows through flow paths 118 and 136 then flows through flow path
138 to a dump source. A continuous flow of precursor gas is
supplied through flow paths 118 and 136 to ensure that there is a
ready supply of precursor gas when the showerhead 122 is ready to
receive the precursor gas.
[0073] In FIG. 4B, the precursor gas is a mixture of carrier gas
and evaporated precursor. Carrier gas flows through flow path 106
and 134, which have open valves 108 and 110 respectively, to enter
the ampoule 102. The ampoule contains evaporated precursor and the
carrier gas mixes with the evaporated precursor to form the
precursor gas. The precursor gas then flows out of the ampoule 102
via the flow path 136.
[0074] FIG. 4C shows an additional step in substrate processing for
the example substrate processing apparatus of FIG. 1A. The step
shown in FIG. 4C corresponds to operation 212 of FIG. 2. In FIG.
4C, valve 128 is now closed, but valve 130 is now open to allow the
precursor gas to flow through the showerhead 122 and into the
processing chamber 132.
[0075] FIG. 4D shows a further step in substrate processing for the
example substrate processing apparatus of FIG. 1A. The step shown
in FIG. 4D corresponds to operation 214 of FIG. 2. In FIG. 4D,
valves 110 and 116 are closed, but valve 124 is open. Thus, there
is no flow of precursor gas through the flow paths, but carrier gas
may flow through flow paths 106 and 118. Additionally, valve 130 is
now closed to prevent the flow of carrier gas into the showerhead
122. Valve 128 is now open to allow the flow of carrier gas to the
dump source.
[0076] In FIG. 4D, valve 114 is open to allow the refilling of
ampoule 102 with precursor. The refilling shown in FIG. 4D is a
secondary precursor refill.
[0077] FIG. 5 is a comparison of substrate processing results for
substrate processing with fill on demand versus substrate
processing without fill on demand. In FIG. 5, the plots represented
by "X" marks are deposition processes utilizing fill on demand,
while the plots represented by square marks are deposition
processes that do not utilize fill on demand.
[0078] As shown in FIG. 5, the deposition processes utilizing fill
on demand have more consistent thicknesses while the deposition
processes that do not utilize fill on demand have greater variances
in their thicknesses. The deposition processes utilizing fill on
demand show greater process uniformity than the deposition
processes that do not utilize fill on demand.
Sensor Levels
[0079] In certain embodiments, additional protections are deployed
to address possible equipment issues such as an ampoule liquid
level sensor malfunction. As mentioned above, the ampoule may have
one or more sensors. In some embodiments, which sense one or more
levels of liquid within the ampoule. In certain implementations, a
single sensor senses two or more levels, and in still further
embodiments, a single sensor senses three or more levels. FIG. 6
depicts an embodiment in which an ampoule 601 has one or more
sensors configured to sense three sensor levels: a full sensor
level 603, a low sensor level 605, and an empty sensor level
607.
[0080] In certain embodiments, the full sensor level is at an
ampoule volume of between about 70% and 90% of the total fill
volume of the ampoule. In certain embodiments, the low sensor level
is at a level of between about 40% and 60% of the total fill volume
of the ampoule. In certain embodiments, the empty sensor level is
set at about 10% to 30% of the total fill volume of the ampoule. In
one example, the full level sensor is marked at about 73% of the
total ampoule volume, the low level sensor or is set at about 48%
of the ampoule volume and the empty level sensor is set at about
12% of the total ampoule volume, which may be about 330 cubic
inches. As further examples, the ampoule volume may be between
about 100 and 1000 cubic inches, depending on the reaction chamber
size and the process(es) supported.
[0081] Various types of physical sensors may be employed to
determine the internal fill level. Examples include single point
and multipoint liquid level sensors such as those available from
Neal Systems, Inc. In some cases, a single physical sensor can
measure two or more levels. In one example, a multipoint sensor is
configured to measure three levels, the full level, the low level,
and the empty level.
[0082] In some implementations, the ampoule control logic employs a
primary check using the full sensor. When the full sensor changes
state from off to on, indicating that the liquid level has reached
the full level, the control logic instructs the fill system to
cease further filling of the ampoule.
[0083] In some implementations, the ampoule control logic employs a
primary check for preventing the ampoule from emptying. This check
may determine that the full sensor has remained in an off state and
fill is not occurred for a set number of cycles, e.g. about 230
cycles for certain ALD processes. In such cases, the control logic
may instruct the system to (i) begin filling (assuming the
deposition process can be gracefully stopped) or (ii) cease
deposition until the ampoule sensor works properly. In some
implementations, the number of cycles in this check is based on the
expected level of consumption of liquid by the ALD process and the
overall volume of the ampoule. For example, in some ampoules,
protection is provided by automatically filling the ampoule every
time a certain mass of liquid is calculated to have been consumed
by the ALD process, for example about 3 to 7 g of liquid.
[0084] If a sensor fails, one or both of the above primary checks
fails. One failure mode occurs when the full sensor, or the
associated software, fails to accurately sense that ampoule liquid
has reached the full level. Additional protections may be built
into the ampoule control logic as described below.
[0085] In certain embodiments, the system is designed or programmed
such that when an illogical sensor reading occurs, the system
enters a soft shutdown or otherwise takes measures to avoid damage
to the system and/or wafers being fabricated. One such illogical
result occurs when a multiple level sensor detects that the full
sensor is on while a lower level sensor is off. This result
suggests that liquid has reached the full level but not the empty
level. Obviously, such state cannot exist.
[0086] In another embodiment, when the lowest level sensor (e.g.,
an empty sensor) of a multiple level sensor is off, the system
automatically takes other precautionary steps. In various
embodiments, the lowest level sensor is designed to trigger a soft
shutdown when it is off because liquid below the lowest level is
deemed to put the ampoule in a state where damage can occur to a
wafer and/or the system itself.
Soft Shutdown
[0087] In certain embodiments, when an error is generated using the
protective measures described in this section or elsewhere
throughout the patent application, the ALD tool or other deposition
tool undergoes a "soft shutdown." In certain embodiments, a soft
shutdown stops the ALD system from performing further deposition
steps or other procedures typically undertaken during normal ALD
processing. In some implementations, a soft shutdown will try to
finish current wafer processing in the chamber, remove the wafers,
and put module in OFFLINE mode. After that, no more wafers will be
processed until the issue with the module is resolved. A soft
shutdown may also stop further ampoule filling if filling is
occurring.
[0088] In certain embodiments, the soft shutdown process generates
a notification to the operator or to a control routine with in the
fabrication facility. The notification may identify the particular
issue that triggered the soft shutdown. Examples of such
notifications may include the empty level sensor being in the off
state, the full level sensor remaining on while cumulative refill
times exceed a threshold, and the full sensor being in the on state
for an extended period; e.g., a period that is greater than a
threshold. Upon review receiving such notification, the control
system and or the operator responsible for maintaining the ALD tool
can take a corrective action intended to fix the notified problem
and allow the ALD tool to resume normal operation. For example, the
operator may fix a malfunctioning sensor, manually adjust and
ampoule liquid level, and the like. After taking such corrective
action, the tool may resume normal operations such as ampoule
refill using a fill on demand procedure as described elsewhere
herein.
Overfill Protection
[0089] In certain implementations, the ampoule fill procedure
includes a routine or other logic for addressing problems caused by
a full sensor showing that it is not on when the system is
operating in a manner where it is expected that it should be on. As
an example, a faulty or malfunctioning sensor might read off when
in fact liquid has reached the level of the sensor, and therefore
the sensor should read on. See sensor level 603 of FIG. 6. To
address this potential issue, the ampoule fill logic maintains a
cumulative time of refill from the end of the last time when the
ampoule was filled. For example, a cumulative timer may reset
whenever the full sensor comes on and the liquid to the ampoule
stopped. If the cumulative time of refilling exceeds the threshold
and the sensor has not yet reached the on state, the logic
initiates a soft shutdown. In other words, anytime the ampoule
needs to be filled, it is assumed that it will not take longer than
{T} time. This time is the total time from multiple number of fill
times (fill requests cumulatively). The ampoule fill logic keeps
track of the total length of the fills and will enter an error
state in the currently running routine if it exceeds {T}. For
example, if F.sub.1=12 s, F.sub.2=40 s, and F.sub.3=12 s, when T=60
s (for example), the logic will enter an error state four seconds
before the end of F.sub.3.
[0090] The threshold for the cumulative timer can be based on
various parameters and typically includes the ampoule fill rate
during the refill operations in question, the ampoule volume
(particularly the maximum volume of liquid expected to provide safe
operation), and the rate of consumption of liquid from the ampoule
during the intervening ALD process steps while the timer is on. It
should be understood that the ALD processes might be performed
between times when ampoule refill operations are performed. In
certain embodiments, the timer threshold is between about 30 and
300 seconds. In certain embodiments, the timer threshold is between
about 50 and 90 seconds (e.g., about 60 seconds). In certain
embodiments, the threshold fill time is determined based on
laboratory test condition using the specific process chemical
consumption rate and ampoule fill rate for the fabrication
facility.
[0091] FIG. 7 presents a flow chart for a specific implementation
of overfill protection. The blocks shown in the flow chart
represent execution steps in a program or other logic for
implementing ampoule fill control in a deposition module. In the
depicted embodiment, the ampoule control logic is represented as a
loop that begins at the start operation 703. During execution, with
each iteration, no particular operation occurs at block 703. In
each iteration, the process logic determines, at a decision point
705, whether the full sensor is in the on state. If so, the
overfill protection portion of the routine is not executed, and the
process proceeds is as described with respect to FIG. 8. In the
overfill protection portion of the routine, the full sensor is not
on, and, as depicted in FIG. 7, the logic provides instructions to
fill the ampoule with precursor as depicted in a block 707.
Concurrently, the process resets a cycle count which may be used in
the empty protection mode as described further with respect to FIG.
8. See block 709. As the fill proceeds, a fill timer keeps track of
the accumulated fill time since last time the fill timer was reset.
See block 711. Next, the ampoule fill logic determines whether the
total accumulated fill time is greater than a threshold value such
as 60 seconds. See decision block 713. If so, the logic puts the
system into an error state and stops executing as depicted in block
715. The system may then enter a soft shutdown is as described
above, and the process ends as depicted at block 717. If the
accumulated time tallied by the fill timer has not exceeded the
threshold, the control logic proceeds from block 713 to a
subsequent decision block 719, where it determines whether the
system is to perform deposition. If not, the routine gracefully
ends at block 717. However, if the logic determines that deposition
is to proceed, the process stops the precursor fill and
concurrently pauses the timer as illustrated in a block 721. It
should be understood that during the course of a deposition
process, the cyclic deposition of material onto the substrate may
pause for wafer indexing, pump to base, and other operations as
described above. Each time this occurs, the ampoule may begin
filling again and the fill timer restarts.
[0092] In the embodiment depicted in FIG. 7, the full sensor
remains in an off state so that ampoule refill occurs whenever
possible, consistent with the underlying fill on demand logic, and
thereby remains in danger of overfilling the ampoule. Returning to
block 721 in the process flow logic, the system begins performing
deposition and then increments a cycle counter as illustrated in
blocks 723 and 725, which will be described in further detail with
reference to FIG. 8. The process control then returns to block 703
where the full sensor is again checked.
[0093] As explained, the logic depicted in FIG. 7 illustrates the
operation of an overfill protection mode and assumes that the full
sensor remains on at all times. In this state, the fill timer keeps
increasing and never gets reset as illustrated at block 711.
Therefore, even if the fill timer is paused repeatedly while
filling stops during the above-described fill on demand algorithm,
the accumulated fill time gets closer and closer to the threshold
and will eventually trigger entry into an error state as
illustrated at block 713 and 715.
[0094] While the protection described in this section is presented
in the context of overfill protection when a full sensor is faulty
or malfunctioning, the protection may extend to other situations
where the full sensor does not turn on but is in fact is performing
properly. For example, the full sensor may remain in an off state
when liquid has not reached its level because there is a
malfunction or other problem in providing liquid to the ampoule.
Examples such problems include a refill valve to the ampoule not
operating properly, slow or no delivery of liquid to the ampoule
from the fabrication facility, and the like. In each of these
cases, the fact that the full sensor remains off for an extended
period of time while ampoule refill is presumably occurring,
suggests that there is a problem, and as such, the ampoule control
logic flags this problem as an error and may initiate a soft
shutdown.
Protection Against Low Ampoule Liquid Levels
[0095] The ampoule control logic in certain embodiments may be
designed to address potential problems caused by a liquid level
sensor showing that it is on when in fact the liquid has not
reached that level. In such cases, the sensor should properly read
off. This malfunction of the sensor were could lead to failure to
refill the ampoule when the liquid level becomes dangerously low.
The primary protection against under fill relies on a sensor
reading off when the liquid level falls below the sensor's read
level. In certain implementations, the control logic provides a
secondary protection by keeping track of precursor cycles from the
last time an ampoule fill is executed. If the number of such cycles
is greater than a threshold number, the system may execute a soft
shutdown.
[0096] In certain embodiments, the ampoule empty protection logic
may include the following features: [0097] During steady state
operation, it is assumed that the ampoule will fill at least once
every {N} deposition cycle. [0098] The control logic keeps track of
the number of cycles since the last fill. [0099] The process module
will be sent into Soft Shutdown if the count exceeds {N}. [0100] If
a fill is actually executed, the count is reset to zero (0). [0101]
{N} is estimated at 5000 cycles (this value is process specific and
can be adjusted based on actual tool)
[0102] FIG. 8 presents the flow chart of FIG. 7 but depicts an
empty protection mode built on top of the fill on demand ampoule
logic. As before, the iterative process determines whether the full
sensor is on as illustrated at a decision block 705. In this
example, it is assumed that the full sensor is malfunctioning by
reading that it is on when in fact it should be off. As
illustrated, when the logic determines a block 705 the full sensor
is on, the ampoule fill logic will stop any current precursor fill.
See block 801. Concurrently, the logic resets the fill timer which
is relevant to the overfill protection routine described with
respect to FIG. 7. After stopping precursor fill at block 801, the
process next determines whether it's time to perform deposition as
illustrated at decision block 719, which was described above.
Assuming that deposition is to be performed, the process logic
instructs the system to perform deposition as illustrated at block
721. As deposition proceeds, each cycle is counted, or at least
those cycles in which precursor is consumed. See block 723. As
cycle count increments over one or more sequential deposition
cycles which may pause periodically for wafer indexing and the
like, a cycle counter compares the current cycle count against some
threshold number of cycles as illustrated at decision block 725. As
explained, the cycle count is determined to protect the ampoule
from becoming dangerously under filled. When the cycle count
ultimately exceeds the threshold--presumably because the full
sensor is faulty or malfunctioning--the process control is directed
to block 715 where it puts the system in an error state and ends
the routine's execution, typically accompanied by a soft shutdown.
Until the time when the cycle count exceeds the threshold, the
process repeatedly loops back to block 703 and 705 where the full
sensor is again checked. Assuming, as is the case here, that the
full sensor remains on, the process proceeds through the branch
including block 801 where deposition continues to occur with no
renewed ampoule filling.
[0103] The chosen cycle threshold may be based on the number of
cycles determined to consume an amount of precursor from the
ampoule that would deplete the liquid level within the ampoule to a
point where it negatively impacts the process (e.g., the deposited
film properties will be negatively impacted). The threshold may be
determined based upon the size of the ampoule, and hence its
responsiveness to changes in level during refill, and the
consumption of liquid precursor per ALD cycle. In certain
embodiments, the cycle threshold is between about 3000 and 8000
cycles. In certain embodiments, the cycle threshold is between
about 4000 and 6000 cycles (e.g., about 5000 cycles). The number of
cycles may correspond to a particular number of wafers processed;
e.g., between about 50 and 100 wafers.
[0104] In certain ALD processes, not every cycle consumes liquid
precursor from the ampoule. For example, one or more ALD cycles
during certain deposition processes intentionally do not draw
precursor from the ampoule. Such "no dose" cycles may be used to
check for the proper functioning of the process and generation of
particles or other problems that may deserve attention. During such
cycles, the liquid level within the ampoule is not reduced.
Therefore, in some implementations, the ampoule control logic
recognizes the cycle as one that does not consume liquid precursor
from the ampoule, and therefore does not included in its count
toward the number of cycles compared against the threshold for an
error state.
Controller Configurations
[0105] In some implementations, a controller is part of a system,
which may be part of the examples described herein. The controller
may include "logic" such as ampoule fill logic or other control
logic discussed herein. Such systems may comprise semiconductor
processing equipment, including a processing tool or tools, chamber
or chambers, a platform or platforms for processing, and/or
specific processing components (a wafer pedestal, a gas flow
system, an ampoule etc.). These systems may be integrated with
electronics for controlling their operation before, during, and
after processing of a semiconductor wafer or substrate. The
electronics may be referred to as the "controller," which may
control various components or subparts of the system or systems.
The controller, depending on the processing requirements and/or the
type of system, may be programmed to control any of the processes
disclosed herein, including the delivery of processing gases,
temperature settings (e.g., heating and/or cooling), pressure
settings, vacuum settings, power settings, radio frequency (RF)
generator settings, RF matching circuit settings, frequency
settings, flow rate settings, fluid delivery settings, positional
and operation settings, refilling of ampoules, wafer transfers into
and out of a tool and other transfer tools and/or load locks
connected to or interfaced with a specific system.
[0106] Broadly speaking, the controller may be defined as
electronics having various integrated circuits, logic, memory,
and/or software that receive instructions, issue instructions,
control operation, enable cleaning operations, enable endpoint
measurements, and the like. The integrated circuits may include
chips in the form of firmware that store program instructions,
digital signal processors (DSPs), chips defined as application
specific integrated circuits (ASICs), and/or one or more
microprocessors, or microcontrollers that execute program
instructions (e.g., software). Program instructions may be
instructions communicated to the controller in the form of various
individual settings (or program files), defining operational
parameters for carrying out a particular process on or for a
semiconductor wafer or to a system. The operational parameters may,
in some embodiments, be part of a recipe defined by process
engineers to accomplish one or more processing steps during the
fabrication of one or more layers, materials, metals, oxides,
silicon, silicon dioxide, surfaces, circuits, and/or dies of a
wafer.
[0107] The controller, in some implementations, may be a part of or
coupled to a computer that is integrated with, coupled to the
system, otherwise networked to the system, or a combination
thereof. For example, the controller may be in the "cloud" or all
or a part of a fab host computer system, which can allow for remote
access of the wafer processing. The computer may enable remote
access to the system to monitor current progress of fabrication
operations, examine a history of past fabrication operations,
examine trends or performance metrics from a plurality of
fabrication operations, to change parameters of current processing,
to set processing steps to follow a current processing, or to start
a new process. In some examples, a remote computer (e.g. a server)
can provide process recipes to a system over a network, which may
include a local network or the Internet. The remote computer may
include a user interface that enables entry or programming of
parameters and/or settings, which are then communicated to the
system from the remote computer. In some examples, the controller
receives instructions in the form of data, which specify parameters
for each of the processing steps to be performed during one or more
operations. It should be understood that the parameters may be
specific to the type of process to be performed and the type of
tool that the controller is configured to interface with or
control. Thus as described above, the controller may be
distributed, such as by comprising one or more discrete controllers
that are networked together and working towards a common purpose,
such as the processes and controls described herein. An example of
a distributed controller for such purposes would be one or more
integrated circuits on a chamber in communication with one or more
integrated circuits located remotely (such as at the platform level
or as part of a remote computer) that combine to control a process
on the chamber.
[0108] Without limitation, example systems may include a plasma
etch chamber or module, a deposition chamber or module, a
spin-rinse chamber or module, a metal plating chamber or module, a
clean chamber or module, a bevel edge etch chamber or module, a
physical vapor deposition (PVD) chamber or module, a chemical vapor
deposition (CVD) chamber or module, an atomic layer deposition
(ALD) chamber or module, an atomic layer etch (ALE) chamber or
module, an ion implantation chamber or module, a track chamber or
module, and any other semiconductor processing systems that may be
associated or used in the fabrication and/or manufacturing of
semiconductor wafers.
[0109] As noted above, depending on the process step or steps to be
performed by the tool, the controller might communicate with one or
more of other tool circuits or modules, other tool components,
cluster tools, other tool interfaces, adjacent tools, neighboring
tools, tools located throughout a factory, a main computer, another
controller, or tools used in material transport that bring
containers of wafers to and from tool locations and/or load ports
in a semiconductor manufacturing factory.
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